Control unit for air driven dental handpieces



M. STAUNT Sept. 13, 1966 CONTROL UNIT FOR AIR DRIVEN DENTAL HANDPIECESl0 Sheets-Sheet 1 Original Filed March 12 1959 INVENTOR. W

M. STAUNT Sept. 13, 1966 CONTROL UNIT FOR AIR DRIVEN DENTAL HANDPIECESOriginal Filed March 2, 1

l0 Shegts-Sheet 2 INVENTOR.

Sept. 13, 1966 M. STAUNT 3,272,229

CONTROL UNIT FOR AIR DRIVEN DENTAL HANDPIECES Original Filed March 12,1959 10 Sheets-Sheet 5 INVENTOR.

f BY M m WW/q/ M M. STAUNT Sept. 13, 1966 CONTROL UNIT FOR AIR DRIVENDENTAL HANDPIECES 1O Sheets-Sheet 4 Original Filed March 12, 1959INVENTOR.

I m M M. STAUNT Sept. 13, 1966 CONTROL UNIT FOR AIR DRIVEN DENTALHANDPIECES 1O Sheets-Sheet 5 Original Filed March 12, 1959 R O T m. V W

M. 'STAUNT Sept. 13, 1966 CONTROL UNIT FOR AIR DRIVEN DENTAL HANDPIECESl0 Sheets-Sheet 6 Original Filed March 12, 1959 INVENTOR. M M

Sept. 13, 1966 M. STAUNT 3,272,229

CONTROL UNIT FOR AIR DRIVEN DENTAL HANDPIECES Original Filed March 12,1959 10 Sheets-Sheet 7 M. STAUNT Sept. 13, 1966 CONTROL UNIT FOR AIRDRIVEN DENTAL HANDPIECES 1O Sheets-Sheet 8 Original Filed March 12 1959INVENTOR. M

Sept. 13, 1966 M, s u T 3,272,229

CONTROL UNIT .FOR AIR DRIVEN DENTAL HANDPIECES Original Filed March 12,1959 10 Sheets-$heet 9 i: all ll INVENTOR.

M. STAUNT Sept. 13, 1966 CONTROL UNIT FOR AIR DRIVEN DENTAL HANDPIECESl0 Sheets-Sheet 10 Original Filed March 12, 1959 United States Patent3,272,229 CGNTRGL UNIT FOR AIR DRIVEN DENTAL HANDPIECES Martin Staunt,Des Plaines, 11]., assignor to American Hospital Supply Corporation,Evanston, Ill., a corporation of Illinois Original application Mar. 12,1959, Ser. No. 798,866. Di-

vided and this application June 10, 1965, Ser. No. 469,028

Claims. (Cl. 137-544) This application is a division of my copendingapplication Serial No. 798,866, filed March 12, 1959, and now abandoned.

The present invention relates to control units for air driven dentalhandpieces, and is particularly concerned with the controls foroperating, controlling, and providing air supply, lubricant supply, andwater supply for the operation of air driven dental handpieces.

One of the objects of the invention is the provision of a control unitwhich assures the delivery of clean air under suitable pressure fordriving an air turbine, clean water under suitable pressure for coolingthe bur, edible lubricant for lubricating the bearings, warm air forblowing out and drying cavities, control of the speed of the handpiece,control of air volume and pressure, control of heated drying air,control of cooling water and the pressure and volume thereof, andcontrol of the grinding operation and the blowing out of chips, withoutneed for removing the handpiece from the mouth of the patient or forusing a hot air syringe.

Another object of the invention is the provision of a control unitstructure which eliminates many piping connections that might leak oil,water, or air, and which eliminates or greatly reduces the possibilityof particulate matter (such as particles of pipe sealing compound) fromgetting into air lines and damaging an air-driven handpiece.

A further object is to provide a control unit structure including aunitary casting board to insure a smooth and unobstructed flow of airand water, thereby eliminating turbulence and bumping which mightotherwise result in rapid wear of the bearings of an air driven dentalhandpiece.

Another object of the invention is the provision of a small, simple, andcompact control unit which provides ample capacity in its conduit sizeswith minimum loss of pressure in the conduits and minimum air turbulencetherein.

Another object of the invention is the provision of an improved mountingunit for such a control, having cored passages leading to outlets forall of the components, each of which may be replaced or servicedindependently of the others, without disturbing pipe connections.

Other objects and advantages of the invention will be apparent from thefollowing description and the accompanying drawings, in which similarcharacters of reference indicate similar parts throughout the severalviews.

Referring to the drawings, of which there are nine sheets,

FIGURE 1 is a view in perspective of the control unit for air drivendental handpieces;

FIGURE 2 is a front elevational view of the unit with the front and rearcovers removed;

FIGURE 3 is a similar rear elevational view;

FIGURE 4 is a top plan view of the manifold casting of FIGURES 2 and 3;

FIGURE 5 is a front elevational view of the manifold casting;

FIGURE 6 is a rear elevational view of the manifold casting;

FIGURE 7 is a sectional view, taken on the line 7-7 of FIGURE 2, lookingin the direction of the arrows;

FIGURE 8 is a sectional view, taken on the plane of the line '88 ofFIGURE 5, looking in the direction of the arrows;

FIGURE 9 is a sectional view, taken on the plane of the line 99 ofFIGURE 5, looking in the direction of the arrows;

FIGURE 10 is an end elevational view, taken on the plane of the line1010 of FIGURE 5, looking in the direction of the arrows;

FIGURE 11 is an end elevational view, taken on the plane of the line1111 of FIGURE 5, looking in the direction of the arrows;

FIGURE 12 is a sectional view, taken on the plane of the line 1212 ofFIGURE 5, looking in the direction of the arrows;

FIGURE 13 is a fragmentary sectional view taken on the plane of the line1313 of FIGURE 11, looking in the direction of the arrows;

FIGURE 14 is a diagrammatic front elevational view showing the manifoldcasting in dotted lines and the course of the water and air in the coredconduits of the control unit casting;

FIGURE 15 is an exploded view in partial section of the parts of thewater pressure regulator valve;

FIGURE 16 is an exploded view showing the parts of one of the needlevalves for controlling the volume and pressure of water or air;

FIGURE 17 is an exploded view in partial section showing the parts ofone of the solenoid valves;

FIGURE 18 is an exploded view showing the parts of the air filter;

FIGURE 19 is an exploded view showing the parts of the water filter;

FIGURE 20 is a view in perspective of the filter element assembly;

' FIGURE 21 is a fragmentary elevational view of the oil trap forremoving lubricant from the exhaust air.

Referring to the drawings in greater detail, the control unit 220(FIGURES 1 and 2) is enclosed in a housing unit 221, the face of whichis provided with a rotating knob 222 controlling the air valve, which islocated in the conduit extending from the source of air pressure to thecontrol unit. The air valve controlled by knob 222 control-s the volumeand pressure of air supplied to the handpiece. The rotated speed of aturbine increases with increased air pressure; therefore, the speed ofoperation may be increased by turning knob 222 in one direction orreduced by turning the knob in the opposite direction.

The unit supports an air gauge 223 connected in the air line extendingfrom the pressure regulator 222 and indicating the pressure of the airapplied to the handpiece turbine and the knob 222 is preferably set sothat the pressure indicated on the gauge 223 is that recommended by theinstruction manual, such as, for example, 20 pounds.

The conduit leading from the source of air supply includes a solenoidvalve, indicated at 224, for turning on and ofi the drive air. 225indicates another solenoid valve for turning on and off the air which issupplied to the handpiece for blowing out and drying the cavity and thisis called the chip 'blower solenoid.

226 indicates the water solenoid valve which controls the flow of waterto a handpiece for cooling a tooth and the grinding bur.

227 indicates the selector control switch which may be used to turn oilthe electric circuits or to turn them to the left to turn on the watersolenoid and the air drive solenoid 224, or to the right to turn on thechip blower solenoid and to provide heat for heating the air used inblowing out and drying a cavity.

The knob 228 controls the needle valve in the water conduit leading tothe water tube of a dental handpiece for adjusting the water sprayintensity and volume, and the knob 229 controls a needle valve in theconduit leading to a handpiece air tube for adjusting the air volume andpressure of warm air issuing from the chip blower of a handpiece.

Referring to FIGURES 4, 5, and 6, these are views of the top, front, andrear of the control unit casting, which is provided with cored conduits,inlets, and outlets for mounting all of the component parts of thecontrol unit. The casting is indicated in its entirety by the numeral230.

Casting 230 is preferably formed of aluminum and is provided with aplurality of forwardly and rearwardly extending foot flanges 231, 232,233, 234, 235, and 236 having suitably threaded apertures for securementto the housing bottom plate 237.

The casting is formed on its front side- 238 with three threaded bores239, 240, and 241 for receiving the soft steel cores which form a partof the solenoid valves 224- 226, further to be described. Each of thebores communicates with an aperture 242, 243, and 244 surrounding acentral body portion 245, 246, and 247, each of which is provided with athreaded aperture for receiving an externally threaded valve seat member248, 249, and 250. The valve seat members have apertures 251, 252, and253 and have frusto-conical surfaces surrounding said apertures.

The aperture 251 in valve seat 248 communicates with a backwardlyextending conduit 254 leading to a vertically extending conduit 255which is threaded at its lower end 256 to receive a threaded stern 257of a needle valve (FIGURE 14) actuated by knob 228 (FIGURES 1-3).

The conduit 255 terminates at its lower end in a tapered bore 258 forreceiving the needle valve, which bore communicates with the lateralconduit 254.

The casting is formed with a water inlet, comprising a threaded bore259a (left side of FIGURE which extends upwardly and is adapted toreceive a pipe extending from a local water supply. Bore 259acommunicates with a cylindrical bore 259 for containing a water filter,to be described hereinafter, and bore 259 ends in a threaded portion 260(FIGURE for receiving the threaded plug 261 (FIGURE 3) which carries thewater filter and which closes the threaded bore.

From the filter chamber 259, a cored conduit 262 extends upwardly(FIGURES 5 and 10) and communicates with the threaded bore 263 which inturn communicates with a smaller rearwardly extending bore 264. Therearwardly extending bore 264 communicates with a laterally extendingcored passage 265 which extends downwardly and communicates with opening242.

The bore 264 is threaded and communicates with a chamber 266 (FIGURE 6)which is adapted to receive a valve seat member 322 having a centralstem 319 extending rearwardly. The chamber 266 ends in a threaded bore269 on the rear side of the unit for receiving the parts of a pressureregulator valve, further to be described.

Referring to FIGURE 3, the numeral 270 indicates a water connectionblock secured to the casting by four screw bolts 271 passing through theblock and threaded into threaded bores 272. The water connection blockhas a laterally extending metal water tube 273 which is in turnconnected to a plastic water hose 274.

The water tube 273 communicates with a lateral conduit 275 in the blockand with a central conduit 276 in the block, communicating with the bore277 leading to the valve opening 251 (FIGURE 5).

Thus, the water is adapted to come in at the inlet 259a to be filteredby the filter in chamber 259. It passes upwardly through cored conduit262 to the pressure regulator valve which regulates its pressure. Thewater then passes downwardly through the conduit 265 to the aperture242, then rearwardly through the solenoid valve aperture 251 to theconduit 258 where it is throttled by the needle valve controlled by knob228; and thereafter the water passes into the conduit 277 leading to theconduits 276 and 275 in the water connection block 270, which deliversthe water to the plastic tube 274, to be carried to the water nozzle ofa dental handpiece.

The casting 230 is, therefore, provided with suitable ports and conduitsfor providing a water inlet leading to a water filter, from the filterto the water pressure regulator valve, from the water regulator valve toa conduit controlled by a needle valve, for determining the amount ofwater, and from the needle valve to the plastic tube which delivers thewater to the handpiece.

Water pressure regulator valve Referring to FIGURE 15, this is anexploded view of the parts of a water pressure regulator valve which ismounted in the threaded bore 269 (FIGURE 6) and the communicating boresleading to the bore 263 on the front side of the unit.

The bore 269 is adapted to receive a threaded plug 300 (FIGURE 15)having a non-circular head 301 and a threaded portion 302 provided witha gasket and threaded into bore 269. The plug 300 has a threaded bore303 for receiving a threaded spring adjustment plug 304, which isprovided with a nut 305 for securing it in any adjusted position, and aslot 306 in its end for receiving a screwdriver blade.

The threaded plug 304 has a cylindrical bore 307 with a reduced portion308 for receiving and seating an adjustment spring 309. The adjustmentspring comprises a helical member of spring bronze formed with aplurality of spaced turns and tapered at its ends 310 and 311 to presentflattened ends engageable with the adjacent parts.

The spring end 311 seats in socket 308. End 310 extends about a lug 312which is formed on an aluminum plate 313 passing through a diaphragm 314of rubber with reenforcing fabric.

The diaphragm 314 is clamped between the plate 313 and a circular disc315 on a threaded lug 316. The lug 316 has a central bore 317 forreceiving and seating the end 318 of stem 319 of water valve 320.

The water valve has a narrow cylindrical metal stem 319 which isanchored in a conical head 321 of rubber adapted to seat in a valve seatmember 322 having external threads 323 and a hexagonal head 325.

The valve seat member 322 is threaded into the bore 264 (FIGURE 5), andvalve 320 is engaged by a spring guide 267 having a socket 268 forreceiving a smaller helical valve spring 326 which in turn is seated ina socket 327 in a closure plug 328. The closure plug has a non-circularhead 329 and .a threaded body 330 supporting a gasket 331. Spring guide267 has another cylindrical socket 268a for receiving the cylindricalend of conical head 321.

When installed in the casting 230, the diaphragm 314 engages an annularshoulder 266a in bore 269, against which it is clamped, adjacent itsouter edge, by annular end 30201 of screw plug 300.

The operation of the water pressure regulator is as follows: Spring 326tends to close the valve 320, the end of which engages the diaphragm314; and spring 309 tends to open the valve 320 and is stronger than thespring 326.

Water entering the conduit at the left of valve 320 (viewed as in FIGURE15) builds up a pressure and acts on the diaphragm, which engages andcompresses spring 309, permitting the spring 326 to close the valve. Thepressure of the water in the conduits on the left side of the diaphragm314 depends on the water pressure connected to the inlet and upon theadjustment of spring 309 by adjustment plug 304.

When the water pressure has built up against the diaphragm 314 to apredetermined level, the valve is closed; but as soon as the pressure onthe water is reduced, the valve is again opened; and the valve continuesto open and close, as required, to maintain a substantially constantpressure of water supplied to the water nozzle of a handpiece.

Air pressure regulator The air pressure regulator, controlled by knob222 and mounted in threaded bore 436 (FIGURE 5), is of substantially thesame construction as the water pressure regulator, except that the airpressure regulator knob 222, which adjusts the tension of a springequivalent to spring 309, is in the form of a knob instead of a headedmember having a slot 306.

The air pressure regulator is mounted in the same type of threadedmember 301a (FIGURE 7) and has a threaded shank 304a, which may besecured in any adjusted position by a pair of lock nuts 305a, since theair pressure is intended to be regulated manually by the user, whereasthe water pressure, when once adjusted, is not to be changed.

Thus, the knob 222 is mounted on the threaded shank 304a, and preferablyhas a substantially cylindrical body 332 formed with a plurality ofgrooves 333 between the lands 334, the latter being knurled forconvenient grip with the fingers. As indicated in FIGURE 1 on the faceof the unit, the air pressure knob adjusts the speed at which theair-driven hand-piece operates, and the speed increases with an increasein the tension or compressive force applied to the spring whichcorresponds with previously-described spring 309.

The amount of air pressure at any adjustment of the knob 222 isindicated on the pressure gauge located in the middle of the front ofthe unit, such gauge being mounted in threaded bore 335 (FIGURE 5).

The operating pressure of 20 pounds per square inch is recommended forthe normal setting of knob 222. This provides an adequate torque,utilizing 1.1 cubic feet of air per minute. By providing hydraulic orelectrical control for adjusting the pressure of the air regulatorspring corresponding with spring 309, the air pressure may be variedfrom 0 to 20 or 25 pounds per square inch; and the same control may beexercised by manually turning knob 222. The speed of operation of thehandpiece may thus be varied manually from 0 to a maximum of 250,000r.p.m. or more by adjustment of knob 222. For bulk removal, 15 to 20pounds gauge pressure is recommended, and for fine finishing of a cavity10 to pounds gauge pressure has been found effective.

Water spray and chip air control The needle valves, actuated by knobs228 and 229, control the volume and pressure of the water spray at thehandpiece, and also control the volume and pressure of heated air forcleaning out and drying cavities. These needle valves, respectivelyactuated by knobs 228 and 229, may be identical in construction, and areinstalled in the threaded bores 336 and 337, respectively (FIG- URE 6).

Referring to FIGURE 16, this is an exploded view of the construction ofthe metering valves for water and chip air. Each valve comprises anelongated stainless steel shank 338 of cylindrical form and providedwith a flattened end portion 339 for receiving the knob 228 or 229.

Each knob comprises a cylindrical member having a socket 340 forreceiving the end of the shank 338 and having a cylindrical body 341provided with a threaded bore 342 for receiving a clamping screw 343 ofthe type having a non-circular socket.

The upper end of the body 341 has grooves 344 and knurled lands 345 forconvenient grip with the fingers.

The shank 338 has a groove 346 containing a rubber O-ring 347 for an airor water seal in the lower end of each bore 336 or 337, which bores arethreaded only at their lower ends to engage the threaded portion 348 ofthe metering valve.

The metering valve preferably has an elongated narrow tapered endportion 349 which is frusto-conical in form and which is adapted to fitinto a complementary bore 350 in a metering valve seat member 351. Themember 351 is threadedly installed in the lower end of bore 337 or 336for forming a valve seat.

A rubber valve seat washer 352 is clamped in the bore 337 (or 336) belowthe valve seat member 351 to insure against leakage, and the meteringvalves are adapted to be adjusted by rotation of the knobs 228 and 229to vary the pressure and flow and volume of water or air.

The solenoid valves 224, 225, and 226 may be identical in construction.Each solenoid valve includes a valve seat member 248, 249, and 250(FIGURE 5). As shown in FIGURE 17, each solenoid valve has a magneticcore member 353 with an enlarged cylindrical externally threaded base354 for reception in each of the bores 239- 241.

Core member 353 has a body 355 of reduced cylindrical shape and athreaded end 356. A peripheral groove 357 extending about the bodycontains a rubber O ring 358. The body 355 supports an insulatedsolenoid coil 359 and the O ring engages inside the cylindrical bore 360of the coil assembly to prevent leakage.

A cover 361, preferably of magnetic metal, is adapted to slide over thecoil 359 and has an aperture 362 for passing the threaded portion 356 ofthe core. The end wall 363 of the cover may have an insert 364 ofmagnetic metal for improving the path for magnetic flux.

A hexagonal sheet metal nut 365 has a threaded aperture 366 for clampingthe cover on the coil. The core 353 has a cylindrical bore 367 forreceiving a solenoid plunger 368, which is preferably of cylindricalform.

The plunger 368 is made of magnetic metal and has a pair of longitudinalgrooves 369 in its opposite sides for passing air out of the bore 367.Plunger 368 has a rubber valve washer 370 mounted in a socket in its endin position to engage and close in one of the valve openings 251 253.

Each plunger has a cylindrical bore 371 in its right end and a coilspring 372 mounted in each bore 371. The spring reacts against the base373 of the bore 367 to urge the plunger and its valve disc 370 intoclosed position. The solenoid valve is opened in each case by passing asuitable current through the coil assembly 359.

A housing end plate 374 of magnetic metal has a cylindrical aperture 375for passing the threaded shank 353 of the core. The end plate fitsagainst the open end 376 of the solenoid housing and completes themagnetic circuit which includes the core 353, housing 361, and end plate374.

Each solenoid valve includes a rear block like the block 270, whichprovides a conduit leading to the plastic hose 274; and the other twoblocks are indicated at 270a and 27% (FIGURE 3) leading to the conduits274a and 27412.

The front of the casting 230 is provided with two forwardly projectinglugs 377 (FIGURE 4) with a pair of threaded bores 378 for mounting aninsulated connector block 379 (FIGURE 2) by means of screw bolts 380.

The connector block comprises an elongated molded insulating memberhaving a multiplicity of molded partitions 381 separating the block intochambers 382 for receiving the screw bolts 383 by means of which thevarious conductors from the solenoids are secured and connected toinsulated wires 384 which lead to the selector switch controlled by knob227.

Air and water filter assemblies The control unit includes an air filter385 (FIGURE 3) which is included in the air line leading from the airinlet.

FIGURE 18 is an exploded view of the parts of the air filter which ismounted on the rear of the unit in a bore 386 (FIGURE 6) leading to asmaller counterbore 387 and a threaded bore 388. The air inlet to thecontrol unit is at 389 (FIGURE 2) and comprises a pipe leading to athreaded bore 390 (FIGURE 4) which communicates with an upwardlyextending cored conduit 391 (FIGURE 6).

The cored conduit communicates through a laterally extending coredconduit 392 (FIGURE 6) with the counterbore 387, and the bore 386 isadapted to receive a rubber gasket 393, forming part of the filterassembly shown in FIGURE 18.

The filter assembly (FIGURE 18) includes an upper supporting screw bolt394 having a knurled head 395 provided with a screwdriver blade slot396. The screw belt 394 has a groove containing an O ring 397 below theannular shoulder 398, and it has a cylindrical body 399 and a reducedthreaded portion 400. A second ring 401 is mounted in a groove at theend of cylindrical body 399.

The supporting screw bolt 394 has a central bore 402 which communicateswith the interior of the filter unit 403. Bore 402 communicates with aplurality of laterally extending bores 404.

The air filter includes an end clamping member 405 having a threadedbore 406 for mounting on the reduced threaded portion 400, and it has asmaller threaded bore 407 in the other end for receiving the threadedend 408 of a central conduit tube 409, which also serves to support theparts of the filter.

Conduit tube 409 has a bore 410 and a pair of through transverseapertures 411 to carry air from the inside of the filter unit 403. Tube409 has a threaded end 412 for securement in a threaded bore 413 in theclamping plate 414 which closes the other end of the filter.

The filter element 403 comprises a brass wire mesh cylinder 415 havingcork washers 416 and 417 at its opposite ends and having a wrapping 418of cotton string forming a cylinder. The wire mesh cylinder 415 has abore 419, and the air to be filtered enters the transparent sleeve 422and passes inward through the wrapped string element 418.

The filter element 403 is clamped between the threaded member 405 at theannular shoulder 420 and against the annular shoulder 421 at the endclamping member 414. The filter element 403 is secured by a transparentcylindrical plastic sleeve 422 which has its upper end engaging therubber gasket 393 in the bore 386.

The lower end of the transparent sleeve 422 engages the rubber gasket423 which is mounted in a bore 424 in the end clamping plate 414 about acylindrical portion 425 which fits inside and centers the plasticsleeve.

The end plate 414 preferably has a cylindrical skirt 426 surrounding theplastic sleeve 422, and has an annular groove 427 for communicating withthe inside of the plastic sleeve 422. A bore 428 extends from the groove427 to an internally threaded sleeve 429 having threads 430 adapted toreceive an ordinary stem valve 431 of the type employed in automobiletires.

Any moisture which collects in the bottom of the filter assembly can bedischarged from time to time by pressing upwardly on the valve stem 432.

The filter assembly is secured together by mounting on the tube 409which is threaded into the end of clamping plate 414 and into the topclamping member 405, completing the assembly. The plastic sleeve 422 ismounted around the filter element.

The screw bolt 394 is threaded into the threaded bore 388 (FIGURE 6) anddraws the filter unit upwardly, clamping the transparent sleeve in thebore 386 against the rubber gasket 393, making an air-tight connection.

The course of air through the filter is as follows: The air comes in atthe cored conduit 391 and passes upwardly and laterally through thecored conduit 392. This leads to the bore 387 and the bore 386 and tothe inside of the transparent sleeve 422.

The air passes inwardly through the string filter element 418 and intothe transverse bores 411 and central bore 410. The central bore 410leads tothe threaded bore 407 in the end clamping plate 405 and goesinto the bore 402 of the screw bolt 394.

The screw bolt 394 is located in bore 388 and has a cylindrical surface399 which is surrounded by the annular groove 433 communicating with thecored conduit 434. The air passing up the bore 402, after beingfiltered, flows out of the apertures 404 into the groove 433 and intothe cored conduit 434 (FIGURE 9).

Cored conduit 434 leads to the bore 435, which extends to the threadedbore 436 for receiving the regulator valve assembly. The outlet from theregulator valve assembly extends downwardly through cored conduit 437 tothe bore 438 and threaded bore 241, which receives the solenoid valveassembly for the air solenoid 224.

Thus, the incoming air is filtered in the filter assembly 385 andcarried to the air regulator valve controlled by knob 222, after whichit passes to the conduits controlled by the solenoid valve 224 so thatthe air is turned off except when the solenoid valve 224 is actuated;and the pressure of the air is constantly regulated by the air pressureregulator valve.

The air filter is adapted to remove 70 percent of part1- cles largerthan 2 microns in size and percent of particles larger than 5 microns insize. It also removes moisture in the air line and, as the air driventurbine operates at high speeds and with extremely small clearances, itis important that the driving air be clean of dust, rust, and otherparticles.

The water filter assembly is shown in an exploded view in FIGURE 19 andis mounted in the threaded bore 260 which is closed by screw plug 261.The screw plug 261 comprises a threaded plug having a non-circular head440 and a threaded body 441 which has a tapered bore 442 ending in acylindrical bore 443. The tapered bore is adapted to receive theresilient soft rubber end plug 444 of the filter unit, such lplugcomprising a resilient member having a cylindrical body 445 providedwith a thorough bore 446 and a radial flange 447 having an annularshoulder 448.

The other rubber end plug 449 may be identical in construction to plug444. The two plugs support a strainer body 450 having a perforatedsupporting housing 451 comprising a perforated sheet of glass having amultiplicity of small apertures 452. The sheet is wrapped into the formof a cylinder with its ends abutting and has a through bore 453.

Another cylinder of fine screen 454 is located in the bore 453 and issupported by the housing 451. The bore formed in the filter unit 450 islarge enough to receive the rubber plugs 445 so that the ends of thefilter unit 450 engage the annular shoulder 448.

The screen of the water filter is sufficiently fine to remove allparticles of rust or other material and is, for example, a 200 mesh persquare inch screen. When the plug 444 is mounted in the tapered bore442, the screw plug closes this end of the filter unit and, when thescrew plug 261 is installed in the bore 260, the filter unit, includingthe perforated body screen and other plug 449, are received in the bore259. I

Bore 259 communicates with cored conduit 262 which in turn communicateswith the annular space 455 surrounding the body 450 of the filter. Thewater inlet 259a communicates with the bore 456, and the water passes inthe aperture 446a of the plug 449 and outwardly through the screen 454and the perforations 452.

From the bore 455, which surrounds the screen, the filtered water passesup the cored conduit 262 which leads to the water regulator valve. Thus,the water is filtered and is cleared of any particles before passingthrough the water regulator valve.

Other components The control unit 220 also includes a lubricator mountedon the rear of the cabinet and indicated in its entirety by the numeral460 (FIGURE 3). This lubricator may be constructed substantially asdisclosed in my prior application, Serial No. 757,062, filed August 25,1958, now Patent 2,943,705. The lubricator is adapted to be supportedupon the casting 230 on its rear. side on a rearwardly projecting lug461 (FIGURE 6) having a flat face and a pair of threaded bores 462.These threaded bores adapted to receive two screw bolts 463 (FIGURE 3)which clamp the lubricator, also called a nebulizer for the reason thatit is adapted to atomize an edible lubricant and introduce the lubricantmist into the air stream of the driven air which drives the air turbineof the dental handpiece controlled by the unit.

The lubricator has its inlet at the ribbed inlet fitting 264 which isconnected by a plastic tube 465 to the outlet tube 274b of the solenoidvalve block 2701) containing conduits extending from the valve port 253and controlled by the drive air solenoid 224. The plastic tube 465carries drive air which has been filtered by the air filter 385, suchair being regulated by the air pressure regulator valve controlled byknob 222 and being delivered to the dental handpiece through the plastichose 466 which is connected to the outlet tube 467 at the top of thelubricator (FIG- URE 3).

The lubricator is adapted to supply the handpiece with lubrication inthe form of a lubricant mist which deposits a film of lubricant on theball bearing races, on the balls, and on the ball retainer, of aturbine-driven dental handpiece. Whenever the drive air is turned on,lubrication is also provided, and also cooling air is directed out ofthe lower end of the handpiece head into a conical stream towards thecutting end of the tool and into the cavity which is being prepared.

An exhaust air oil trap is also illustrated in FIGURE 3, beingdesignated by the numeral 550.

Since the drive air contains oil mist, it is important that the exhaustair be carried away from the handpiece and from the vicinity of thepatient and the dentist, and that the oil be removed from the air, suchremoval occurring at the control unit.

The exhaust air oil trap may be mounted on the casting of the controlunit by means of a cylindrical metal band 551 which embraces and clampsthe transparent plastic vial 552. The band is secured by one of thescrew bolts 553 threaded into a threaded bore 27211 in the casting, suchbolt being one of the bolts which also secures the conduit block 270a onthe rear end of the conduits extending from the solenoid valve assembly225.

As shown in FIGURE 21, vial 552 has an upper threaded end 554 forreceiving a metal screw cap 555, such cap having a multiplicity ofthrough apertures 556 in its upper wall 557. The screw cap 555 has abrass tube 558 braised or soldered in its upper wall 557 and extendinginto the vial 552 a distance substantially half the length of the vial(FIGURE 21).

The lower end 559 of the tube 558 is open; and the upper end of the tube558 has a peripheral rib 560 for receiving the plastic tube 561, whichis larger than the air supply tube that brings the driving air to theturbine. Inside the cap 555 and vial 552 and tube 558 is provided withan oil filter 562 comp-rising a plug of cotton gauze large enough toclose the upper end of the vial 552 and adapted to absorb any oilremaining in the air before the air passes out of the apertures 556.

After the driving air has delivered its power to the turbine of thedental handpiece, the exhaust air, which may still contain some oilmist, is returned through the flexible tube 561 to the oil trap. Theexhaust air is carried down to the middle of the vial 552 and itsdirection is reversed as it passes out of the end 559 of the tube 553and goes upwardly through the gauze plug 562 and out through apertures556. Some of the entrained oil is condensed on the walls of the vial 552where it can be observed and emptied from time to time. Any remainingair must pass through the gauze filter plug 562 before it emerges fromthe top, and this filter element absorbs the remaining oil from the airso that the air which emerges is substantially free of entrained oil.

It will thus be observed that I have invented an improved control unitfor air driven dental handpieces and an improved supply system wherebythe air driven handpiece may be driven at any desired speed bymanipulating the knob 222 on the control unit; and simultaneously airand water are directed on the but from all sides for cooling the bur andthe cavity walls.

The present control unit and supply system includes everything that isnecessary for the continuous and efficient operation of the air drivenhandpiece and for its lubrication and supply of air which is free fromparticles or water which might injure the bearings or the parts of theturbine.

While I have illustrated a preferred embodiment of my invention, manymodifications may be made without departing from the spirit of theinvention, and I do not wish to be limited to the precise details ofconstruction set forth, but desire to avail myself of all changes withinthe scope of the appended claims.

I claim:

1. A supply system for air driven dental handpieces, comprising a basecasting having a first conduit with a threaded inlet bore to beconnected to a supply of air provided by an air compressor, said firstconduit extending to an enlarged bore communicating with a smallercounterbore, an air filter assembly having a cylindrical plug providedwith an O ring engaging in said counterbore to seal one open endthereof, said plug having a bore communicating with a second inletforming an outlet for the filter, a tube in said bore, a cap on the endof said tube, a filter element on said tube receiving air from saidenlarged bore and passing air inwardly to apertures in said tube, and atransparent cylinder mounted between said casting and said cap andestablishing a closed container about said filter element, said castinghaving a second enlarged threaded bore communicating with the outlet ofthe filter assembly, and a pressure regulator valve in said secondenlarged bore communicating with a third conduit for dischargingfiltered air at reduced pressure to a pair of enlarged bores eachcontaining a solenoid valve controlling air.

2. The structure of claim 1 in which said casting is provided with asecond laterally extending conduit from said first bore to a second rearopening providing a front valve opening, a solenoid valve carried by athreaded bore in said front valve opening, a rear cover plate having ametal tube for discharging air to a flexible tube, said flexible tubeextending to a lubricator providing a lubricant reservoir for supplyingnebulized lubricant to air flowing from said flexible tube.

3. A supply system for air driven dental handpieces, comprising a basecasting having a first conduit with a threaded inlet bore to beconnected to a supply of air provided by an air compressor, said firstconduit extending to an enlarged bore communicating with a smallercounterbore, an air filter assembly having a cylindrical plug providedwith an O ring engaging in said counterbore to seal one open endthereof, said plug having a bore communicating with a second conduitforming an outlet for the filter, a tube in said bore, a cap on the endof said tube, a filter element on said tube receiving air from saidenlarged bore and passing air inwardly to apertures in said tube, and atransparent cylinder mounted between said casting and said'cap andestablishing a closed container about said filter element, said castinghaving a second enlarged threaded bore communicating with the outlet ofthe filter assembly, a pressure regulator valve in said second enlargedbore communicating with a third conduit for discharging filtered air atreduced pressure to a pair of enlarged bores each containing a solenoidvalve controlling air, the latter enlarged bores each supporting athreaded plug and having a tube supporting a pair of end plates clampinga cylindrical housing surrounding a coil on the tube, a magnetic corearmature in the tube engaging a spring and engaging a valve seat in eachof said latter enlarged bores.

4. A supply system for air driven dental handpieces comprising a basecasting having a first conduit with a threaded inlet bore to beconnected to a supply of air provided by an air compressor, said firstconduit extending to an enlarged bore communicating With a smallercounterbore, an air filter assembly having a cylindrical plug providedwith an O ring engaging in said counterbore to seal one open endthereof, said plug having a bore communicating with a second conduitforming an outlet for the filter, a tube in said bore, a cap on the endof said tube, a filter element on said tube receiving air from saidenlarged bore and passing air inwardly to apertures in said tube, and atransparent cylinder mounted between said casting and said cap andestablishing a closed container about said filter element, said castinghaving a second enlarged threaded bore communicating with the outlet ofthe filter assembly, a pressure regulator valve in said second enlargedbore communicating with a third conduit for discharging filtered air ata reduced pressure to a pair of enlarged bores each containing asolenoid valve controlling the flow of air, and a fourth conduitcommunicating with one of said pair of enlarged bores for conducting airfrom said pressure regulator valve to a lubricator assembly forproviding the filtered and pressure-controlled air with a lubricantmist.

5. An air control assembly for dental handpieces, comprising a unitarycasting having an air inlet for air under pressure, said air inletcommunicating with a first conduit extending to a second transverseconduit communicating with an air filter for removing the moisture andsolids from the air, said air filter discharging air through a thirdconduit in said casting having a threaded closure plug and having avalve opening opposite to said plug and leading to an enlargedcounterbore, a pressure regulator valve in said counterbore for reducingthe pressure of air discharged from said counterbore, said pressureregulating valve having a diphragm in said enlarged counterbore andsubject to air under pressure therein from said valve opening, saiddiaphragm engaging a valve in said opening responsive to air pressure onsaid diaphragm, said counterbore communicating with a fourth conduitextending to a threaded bore having a valve opening therein, a solenoidvalve disposed in said last-mentioned threaded bore for opening andclosing said valve opening and for controlling the flow of air to an airoutlet, said outlet leading to an aperture closed by a plate having ametal tube conducting air to a flexible hose carried by said tube, saidtube being connected to and communicating With a lubricator forintroducing a lubricant mist into the air flowing from said tube.

References Cited by the Examiner UNITED STATES PATENTS 2,612,728 10/1952Jaoobsson 137-544 XR 2,855,672 10/1958 Frannick et al 3228 M. CARYNELSON, Primary Examiner.

HENRY T. KLINKSIEK, Examiner.

1. A SUPPLY SYSTEM FOR AIR DRIVEN DENTAL HANDPIECES, COMPRISING A BASECASTING HAVING A FIRST CONDUIT WITH A THREADED INLET BORE TO BECONNECTED TO A SUPPLY OF AIR PROVIDED BY AN AIR COMPRESSOR, SAID FIRSTCONDUIT EXTENDING TO AN ELONGATED BORE COMMUNICAING WITH A SMALLERCOUNTERBORE, AN AIR FILTER ASSEMBLY HAVING A CYLINDRICAL PLUG PROVIDEDWITH AN O RING ENGAGING IN SAID CONTERBORE TO SEAL ONE OPEN END THEREOF,SAID PLUG HAVING A BORE COMMUNICATING WITH A SECOND INLET FORMING ANOUTLET FOR THE FILTER, A TUBE IN SAID BORE, A CAP ON THE END OF SAIDTUBE, A FILTER ELEMENT ON SAID TUBE RECEIVING AIR FROM SAID ENLARGEDBORE AND PASSING AIR INWARDLY AIR APERTURES IN SAID TUBE, AND ATRANSPARENT CYLINDER MOUNTED BETWEEN SAID CASTING AND SAID CAP ANDESTABLISHING A CLOSED CONTAINER ABOUT SAID FILTER ELEMENT, SAID CASTINGHAVING A SECOND ENLARGED THREADED BORE COMMUNICATING WITH THE OUTLET OFTHE FILTER ASSEMBLY, AND A PRESSURE REGULATOR VALVE IN SAID SECONDENLARGED BORE COMMUNICATING WITH A THIRD CONDUIT FOR DISCHARGINGFILTERED AIR AT REDUCED PRESSURE TO A PAIR OF ENLARGED BORES EACHCONTAINING A SOLENOID VALVE CONTROLLING AIR.